#include<bits/stdc++.h>
#define C 0.5772156649
#define pi acos(-1.0)
#define ll long long
#define mod 1000000007
#define ls l,m,rt<<1
#define rs m+1,r,rt<<1|1
#pragma comment(linker, "/STACK:1024000000,1024000000")using namespace std;const double g=10.0,eps=1e-7;
const int N=300000+10,maxn=100+10,inf=0x3f3f3f3f3f;bool vis[30];
int main()
{ios::sync_with_stdio(false);cin.tie(0);int n;string s;cin>>s>>n;int ans=0;for(int i=0;i<s.size();i++){if(!vis[s[i]-'a']){vis[s[i]-'a']=1;ans++;}}if(n>s.size())cout<<"impossible"<<endl;else cout<<max(0,n-ans)<<endl;return 0;
}
/****************************************/

n,m = input().strip().split()
n = int(n)
m = int(m)
a = [([0]*50) for i in range(50)]
for i in range(n):p=input()a[i] = p.split(' ')
ans = 0
for i in range(n):k = 0for j in range(m):if a[i][j] == '1':k = k+1ans=ans+2**k-1+2**(m-k)-1
for i in range(m):k = 0for j in range(n):if a[j][i] == '1':k = k+1ans=ans+2**k-1+2**(n-k)-1
print(ans-n*m)

#include<bits/stdc++.h>
#define C 0.5772156649
#define pi acos(-1.0)
#define ll long long
#define mod 1000000007
#define ls l,m,rt<<1
#define rs m+1,r,rt<<1|1
#pragma comment(linker, "/STACK:1024000000,1024000000")using namespace std;const double g=10.0,eps=1e-7;
const int N=50+10,maxn=1000000+10,inf=0x3f3f3f;int a[N][N];
int main()
{ios::sync_with_stdio(false);cin.tie(0);ll n,m;cin>>n>>m;for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)cin>>a[i][j];ll ans=-n*m;for(int i=1;i<=n;i++){ll k=0;for(int j=1;j<=m;j++)if(a[i][j]==1)k++;ans+=(1ll<<k)-1;ans+=(1ll<<(m-k))-1;}for(int i=1;i<=m;i++){ll k=0;for(int j=1;j<=n;j++)if(a[j][i]==1)k++;ans+=(1ll<<k)-1;ans+=(1ll<<(n-k))-1;}cout<<ans<<endl;return 0;
}
/****************************************/

#include<bits/stdc++.h>
#define C 0.5772156649
#define pi acos(-1.0)
#define ll long long
#define mod 1000000007
#define ls l,m,rt<<1
#define rs m+1,r,rt<<1|1
#pragma comment(linker, "/STACK:1024000000,1024000000")using namespace std;const double g=10.0,eps=1e-7;
const int N=100000+10,maxn=100+10,inf=0x3f3f3f3f3f;int a[N],b[N];
bool vis[N];
map<int,int>m;
vector<int>v[N];
int main()
{ios::sync_with_stdio(false);cin.tie(0);int n;cin>>n;for(int i=1;i<=n;i++){cin>>b[i];a[i]=b[i];}sort(b+1,b+1+n);for(int i=1;i<=n;i++)m[b[i]]=i;int cnt=0;for(int i=1;i<=n;i++){if(!vis[i]){++cnt;int p=i;while(m[a[p]]!=i){vis[m[a[p]]]=1;v[cnt].push_back(m[a[p]]);p=m[a[p]];}v[cnt].push_back(m[a[p]]);}}cout<<cnt<<endl;for(int i=1;i<=cnt;i++){cout<<v[i].size();for(int j=0;j<v[i].size();j++)cout<<" "<<v[i][j];cout<<endl;}return 0;
}
/****************************************/

#include<bits/stdc++.h>
#define C 0.5772156649
#define pi acos(-1.0)
#define ll long long
#define mod 1000000007
#define ls l,m,rt<<1
#define rs m+1,r,rt<<1|1
#pragma comment(linker, "/STACK:1024000000,1024000000")using namespace std;const double g=10.0,eps=1e-7;
const int N=50000+10,maxn=100+10,inf=0x3f3f3f3f3f;int main()
{srand(time(NULL));ios::sync_with_stdio(false);cin.tie(0);int st,n,x;cin>>n>>st>>x;vector<int>v;for(int i=0;i<n;i++)v.push_back(i+1);random_shuffle(v.begin(),v.end());int ans=-1,p=st;for(int i=0; i<min(n,1600); i++){cout<<"? "<<v[i]<<endl;cout.flush();int v,id;cin>>v>>id;if(v>ans&&v<=x){p=id;ans=v;}}while(p!=-1&&ans<x){cout<<"? "<<p<<endl;cin>>ans>>p;}if(ans<x)ans=-1;cout<<"! "<<ans<<endl;cout.flush();return 0;
}
/****************************************/